Cell membranes made up of lipid bilayers are naturally heterogeneous, and the molecular dynamics of such layers are integral for molecular transport through cells. The molecular dynamics of cell membranes are highly affected by the chemical makeup of the membrane layers. Living membranes consist of a mix of glycerophospholipids such as DOPC (1,2-Dioleoyl-sn-glycero-3-phosphocholine), POPC (1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and DPPC (1,2-Dipalmitoyl-sn-glycero-3-phosphocholine), the sphingophospholipid PSM (N-palmitoyl-D-erythro-sphingosylphosphorylcholine) and the sterol cholesterol, a lipid which is vital for maintaining membrane structure and function. To systematically understand how lipid composition affects membrane properties, we study systems of single-component membranes, binary-component membranes with one phospholipid and cholesterol and ternary-component membranes with two phospholipids and cholesterol at 310 K and 340 K. Our goal is to understand how compositional heterogeneity affects the dynamic heterogeneity of the membrane. Our findings show that decreasing the number of double bonds in the tails of the glycerophospholipids of a membrane increases structure and lowers mobility of the membrane as a whole. When the number of these double bonds decreases, as in when the degree of saturation increases, density and lipid tail orientation increase. Thus the addition of unsaturated glycerophospholipids to any membrane system substantially reduces the collective nature of lipid motions, while the addition of DPPC, sphingomyelin and cholesterol increase structure and dynamic heterogeneity. In general the level of clustering in our systems is rather small. The membranes with DPPC and PSM exhibit the highest level of clustering. Our findings may offer insights into a range of dynamical processes in living systems, including lipid rafts, protein transport across membranes, anesthetic function, cytoskeletal interactions and cryopreservation.
"},{"label":"Degree","value":["Bachelor of Arts with Departmental Honors"]},{"label":"Administrative Note","value":"Drupal Node ID: 24228